[Simple quantitation of arsenic by energy dispersive fluorescence X-ray spectrometer using Reinsch's test]

We examined the clinical usefulness of the Reinsch's test for the detection of the small amounts of the heavy metals such as arsenic and mercury using the fluorescence X-ray spectrometry. We tried t o measure various kinds of biological samples, including serum, urine, and gastric contents using this method. 0.4 ml or 1 ml of hydrochloric acid were added to 2 ml of serum or 6 ml urine and gastric content, respectively, and a copper plate (5.0x 0.8 cm) was immersed into this solution. The mixture heated at 90 degrees C by a heating block for 30 minutes. After heating, the copper plate was washed with water and dried. The copper arsenide that stuck to the copper plate due to Reinsch's test dissolved by methanol/ammonia (8:2) solution at 60 degrees C for 15 minutes. A drop gave the solution to a filter paper fluorescence X-ray analysis and completely dried the filter paper, and applied to the fluorescence X-ray spectrometer. As a result, this method showed about 20 times high sensitivity in comparison with the measurement with condition of solution. The minimal detectable limits of rsenic was 0.4 ppm in serum and were 0.2 ppm in rine and gastric content. The calibration curve could be made for 0.5 to 50 ppm. It will take about 90 min for the measurement using this method for the detection of arsenic in biological samples. We showed the usefulness of the Reinsch's test using the fluorescence X-ray spectrometry in the clinical toxicology.